Nothing says power like a seat in the Oval Office: In NBC’s “State of Affairs,” premiering Nov. 17, Alfre Woodard confronts vital security issues as the president of the United States. Photo: Michael Parmelee/NBC

Clad in a power wardrobe of form-fittting suits and leather jackets, actress Viola Davis plays a hard-hitting law-school professor in “How to Get Away With Murder,” airing Sept. 25 on ABC.Photo: Nicole Rivelli/ABC

An amazing thing happened when the major networks announced their fall schedules in May. At least half a dozen series had minority actors in the lead roles.

Taraji P. Henson, who is going to co-star with Terrence Howard in the midseason Fox music-industry drama “Empire,” had been the third lead on CBS’ “Person of Interest” for several seasons. Now, she finally receives that star-of-the-show upgrade befitting any Oscar nominee.

After propping up more white stars than you can shake a stick at in movies and on TV, the mighty Viola Davis finally gets the Kerry Washington treatment: She’s no longer wearing the maid’s uniform in “The Help,” but playing an enigmatic and fierce law-school professor on the new Shonda Rhimes drama “How To Get Away With Murder” on ABC.

Octavia Spencer, her Oscar-winning co-star from “The Help,” gets top billing in another Fox series, “Red Band Society,” as a sympathetic nurse in a children’s cancer ward. And you couldn’t ask for a more powerful role than the one Alfre Woodard has on the new NBC political drama “State of Affairs.” She’s playing the president of the United States.

Why is diversity all the rage now? Pearlena Igbokwe, executive vice president of drama programming at NBC Universal, thinks the trend is a sign of the times: “We currently have an African- American president. In a few years, I think we will have a female president. We cast Alfre because she is an amazing actress and because she has gravitas . . . The role was written for a female president of any ethnic background and now we have an African-American actress playing the president, but we don’t feel it’s much of a stretch at all. She does have that bearing.”

Joe Morton, who just won his first Emmy award for playing Kerry Washington’s father on ABC’s “Scandal,” says, “The industry has finally caught up to its audience. People would like to see the world they live in, portrayed realistically. TV is beginning to open the lens and look around.”

To that end, ABC programming chief Paul Lee has encouraged his showrunners to push past the confines of conventional television. Larry Wilmore, executive producer of “Blackish,” a fall comedy about an African-American family wondering if success has cost them some of their cultural identity, says, “When [executive producer] Kenya Barris came up with the title of our show, we thought we were going to get pushback, but Paul embraced the subversive nature of the show.”

The diversity revolution can also be attributed to the success of ABC’s “Scandal” and its game-changing creator Rhimes, who will own Thursday nights on the network this fall with long-running hit “Grey’s Anatomy” at 8 p.m., the Kerry Washington drama at 9 p.m. and a new legal drama, “How To Get Away With Murder,” at 10 p.m. With “Scandal” commanding $200,970 per 30-second advertising spot, it’s a cash cow.

“The color Hollywood loves the most is green,” says Wilmore. “Shonda Rhimes really showed that you can have a black lead in your thriller and you can have a great show. She broke down that wall, and Hollywood follows success.”

Rhimes is most often cited as the trailblazer who delivered one hit after another without resorting to male-centric crime procedurals. In a time of wandering audiences, her track record let nervous network executives put down their liter-size bottles of Mylanta — and gave courage to other producers.

Rina Mimoun, executive producer of “Red Band Society,” says that, because of the Rhimes effect, “people will open up their casting. There’s no reason not to.”